Authors:L. C. Morais, J. Dweck, F. R. Valenzuela-Diaz, and P. M. Büchler
The treatment of the effluents of dairy product industries containing lactose is done by a biological process, which reduces considerably the original amount of that sugar. Although the final residual content of lactose is small after treatment, it may cause the eutrophication and/or the superfertilization of the water, which provokes vegetation growth on the water surface, hindering the navigability and increasing the consumption of the dissolved oxygen necessary to the life of the fishes of the river or sea where the treated effluent is poured. In dairy industry, after proper initial processing steps of waste treatment, lactose, as it is water soluble, may still be present in the outgoing effluents. A complementary step by using organophilic clay adsorption, as a further treatment of these effluents, may enhance antipollution procedures, decreasing its final content in the effluents. The present paper deals with the characterization, by thermal analysis of different lactose products, which may be present in the different processing steps as it dissolves in water and then it is recrystallized from it, as well as after being adsorbed by organophilic clay from those effluents, which are very diluted lactose aqueous solutions.
Authors:J. Giusti, G. G. T. Guarini, L. Menabue, and G. C. Pellacani
The thermal behaviour of single-crystals of the title compound has been investigated by means of thermal methods supported by optical microscopy. A complex change takes place on heating. After the loss of the two water molecules, leading to an amorphous phase, recrystallization takes place. This results in a solid (probably an anhydrous form) which reacts further, through partial liquefaction, to yield a red crystalline product whose structure has been characterized via X-ray powder spectra and electronic and IR spectroscopy.
In mineralogical research differential thermal analysis can be applied as either a single or a combined method for three purposes:1.for the qualitative identification of minerals and the (semi-)quantitative determination of the components of rocks and soils,2.for the characterization of crystal-physical and crystal-chemical properties, including the study of kinetics and the determination of thermodynamic data, phase and reaction equilibria,3.for special petrogenetic investigations concerning the interrelation of mineralogical properties with the formation, decomposition or recrystallization of minerals.
Authors:P. Claudy, J. M. Letoffe, J. J. Counioux, and R. Cohen-Adad
The non-equilibrium region of the phase diagramxLiCl-(1−x)H2O (0<x< 0.18) has been studied by means of a Mettler TA 2000 B heat flow differential scanning calorimeter. The metastable lines of the diagram have been established and the different phases obtained explained. A region has been found where the glass formed cannot recrystallize, the eutectic line being below the temperature of the transition glass.
Authors:R. Brodzinski, H. Miley, J. Reeves, and F. Avignone
Three years ago, state-of-the-art low-background germanium spectrometry was discussed, and speculations were advanced as to the origin of the remaining background. Some of those speculations have been shown to the incorrect. Contemporary lead shielding contains 100 Bq/kg of210Pb. Our 450-year-old lead was shown to contain <100 mBq/kg A high purity electroformed copper Marinelli shield was placed around the detector with no efffect on the background, which implied that the source is other than the 450-year-old shield. A new limit on the210Pb in this old lead shield is <9 mBq/kg. Electroformed copper components were found to contain226Ra and228Th contaminations at levels of 3500 and 110 Bq/kg, respectively. High purity H2SO4, recrystallized CuSO4, and a BaSO4 scavenge in the electroforming bath have reduced these contaminations to <25 and 9 Bq/kg, respectively. In copper, cosmic ray induced nuclear reactions are now the dominant source of raioactivity. For example,58Co can be readily measured after only a 24-hour exposure at sea level. A new germanium spectrometer containing 2150 grams of 87.44% enriched76Ge has been fabricated to mitigate the effect of cosmogenic68Ge in the background. Current background spectra are presented, and potential sources identified.
Authors:Noufissa Zanati, Michael Mathews, Indika Perera, John Moran, Jean Boutros, Alan Riga, and Mekki Bayachou
The long-term goal of this investigation is to study the effects of increased cholesterol levels on the molecular activity
of membrane-bound enzymes such as nitric oxide synthase, that are critical in the functioning of the cardiovascular system.
In this particular investigation, we used differential scanning calorimetry (DSC) and dielectric thermal analysis (DETA) to
study the effect of added cholesterol on melting/recrystallization and dielectric behavior, respectively, of phosphatidylcholine
(PC) bilayered thin films. We also used electrochemical methods to investigate the effect of added cholesterol on the redox
behavior of the oxygenase domain of nitric oxide synthase as a probe embedded in the PC films. The results show that added
cholesterol in the PC films seems to depress the molecular dynamics as indicated by lowered current responses in the presence
of cholesterol as well as a slight increase of the transition temperature in the overall two-phase regime behavior observed
in PC–cholesterol films. These results are rationalized in the context of the general DSC and DETA behaviors of the PC–chol
We studied thermal transitions and physical stability
of oil-in-water emulsions containing different milk fat compositions, arising
from anhydrous milk fat alone (AMF) or in mixture (2:1 mass ratio) with a
high melting temperature (AMF–HMT) or a low melting temperature (AMF–LMT)
fraction. Changes in thermal transitions in bulk fat and emulsion samples
were monitored by differential scanning calorimetry (DSC) under controlled
cooling and reheating cycles performed between 50 and –45C (5C
min–1). Comparison between bulk fat samples
and emulsions indicated similar values of melting completion temperature,
whereas initial temperature of fat crystallization (Tonset)
seemed to be differently affected by storage temperature depending on triacylglycerols
(TAG) composition. After storage at 4C, Tonset
values were very similar for emulsified and non-emulsified AMF–HMT blend,
whereas they were lower (by approx. 6C) for emulsions containing AMF
or mixture of AMF–LMT fraction. After storage at –30C, Tonset values of re-crystallization
were higher in emulsion samples than in bulk fat blends, whatever the TAG
fat composition. Light scattering measurements and fluorescence microscopic
observations indicated differences in fat droplet aggregation-coalescence
under freeze-thaw procedure, depending on emulsion fat composition. It appeared
that under quiescent freezing, emulsion containing AMF–LMT fraction
was much less resistant to fat droplet aggregation-coalescence than emulsions
containing AMF or AMF–HMT fraction. Our results indicated the role of
fat droplet liquid-solid content on emulsion stability.
Authors:Z. Mohd Ishak, P. Shang, and J. Karger-Kocsis
The polymerization of a cyclic butylene terephthalate
(CBT) oligomer was studied as a function of temperature (T=200
and 260C, respectively) by modulated DSC (MDSC). The first heating was
followed by cooling after various holding times (5, 15 and 30 min) prior to
the second heating which ended always at T=260C.
This allowed us to study the crystallization and melting behavior of the resulting
polybutylene terephthalate (PBT), as well. In contrary to the usual belief,
the CBT polymerization is exothermic and the related process is superimposed
to that of the CBT melting. The melting behavior of the PBT was affected by
the polymerization mode (performed below or above the melting temperature
of the PBT product) of the CBT. Annealing above the melting temperature of
PBT yielded a product featuring double melting. This was attributed to the
presence of crystallites with different degrees of perfection. The crystals
perfection which occurred via recrystallization/remelting was manifested by
a pronounced exothermic peak in the non-reversing trace.
Authors:M. Z. El Sabee, W. G. Perkins, R. S. Porter, V. G. Baranov, and S. Ya. Frenkel
The thermal and mechanical behaviour was measured in the U. S.for a polyethylene that had been prepared and highly drawn in the U. S. S. R. The melting point and percent crystallinity were evaluated in this studies as a function of heating rate and recrystallization. The Young's modulus and tensile stress to break in the orientation direction were 4.1 and 0.15 GPa, respectively.The tensile strain to break was about 8%.
The thermal decomposition of four commercial powders and of differently stored single crystals of sodium hydrogen carbonate
is studied by power compensation DSC and by optical and FT-IR microscopy. Independently of manufacturer, specified purity
and price, the thermal curves of all the commercial powders show a more or less pronounced low temperature peak preceding
the one due to the main decomposition. Such small peak is not observed when samples of laboratory recrystallized material
are used. However the thermal behaviour of the latter preparation differs remarkably depending on storage conditions: the
material kept in closed glass containers decomposes at temperatures higher than those of the material stored in a dessiccator
in the presence of concentrated H2SO4.
The observation by optical microscopy of the behaviour of the surfaces of single crystals coming from different storage conditions
when the temperature is raised in a Kofler heater helps the interpretation of the data collected.
The mechanism of the decomposition is discussed and the relevant kinetic parameters reported.